1. Field of the Invention
The present invention relates generally to the field of immunoconjugates. More specifically, the invention relates to conjugates of monoclonal antibodies and biological response modifiers.
2. Description of the Related Art
Biological response modifiers exhibit a variety of effects upon a number of cell types. Mammalian cells produce lymphokines and cytokines to maintain homeostasis at the cellular level. At physiological or in pharmacological concentrations, biological response modifiers such as the interferons, the interleukins and tumor necrosis factor (TNF) all have cytotoxic effects. TNF has pleotropic and anti-tumor effects on animal and human tumor cells in vitro and in vivo. Recombinant human TNF has been shown to cause tumor necrosis of sarcoma, adenocarcinomas, and melanomas. TNF has divergent effects on cell growth, causing antigrowth effects on some cell lines, virtually no effect on other lines, and growth enhancement of other cells. TNF may also increase bone-resorption and enhance pro-coagulant activity of endothelial cells.
When drugs or other cytoactive agents are administered to an individual, many, if not all, are diluted in the host body and are, to a certain extent, metabolized by the host tissues. Thus, in many cases these cytoactive agents must be administered in much higher amounts than are necessary to achieve the desired effects in order to account for the dilution, absorption, and metabolism by non-target tissues.
Cancer is one of the leading causes of mortality and morbidity in the Western world. Breast cancer and cervical cancer are two of the leading causes of death from malignancy in women in the Western world. Melanoma is a highly metastatic disease affecting both sexes and is almost uniformly fatal within five years of diagnosis. Surgical removal of localized malignancies has proven effective only when the disease has not spread beyond the primary lesion. Once the disease has spread, the surgical procedures must be supplemented with other more general procedures to eradicate the diseased or malignant cells. Most of the commonly utilized alternative therapeutic modalities such as irradiation or chemotherapy do not confine their effects solely to the tumor cells and, although they have a proportionally greater destructive effect on malignant cells, often affect normal cells to some extent.
Many tumors or cancer cells express membrane-bound or cytoplasmic antigens or antigenic determinants which are either expressed very weakly or not at all by normal cells. Some tumor cells express antigens also found in or on embryonic cell types but are not expressed by normal cells of a mature animal. These abnormally expressed antigens are known as tumor-associated antigens. These tumor-associated antigens may be expressed on the surface of the cell (cell surface antigen), may be secreted by the tumor cell (secreted antigens) or may remain inside the cell (intracellular antigen). While membrane-bound or cell-surface antigens are believed to play a major role in the interaction between tumor cells and the host""s immune system, cytoplasmic antigens are also useful for monitoring neoplasia since these antigens are often shed in large amounts by the tumor cells.
Antibodies are proteins normally produced by the immune system of an animal in response to foreign antigens or antigenic determinants. Antibodies bind to the specific antigen to which they are directed. Monoclonal antibodies directed to specific antigens or antigenic determinants may be prepared in large quantities. Monoclonal antibodies to tumor associated antigens localize in tumors after systemic administration to patients with cancer.
Antibodies, coupled to drugs, have been used as a delivery system by which the drug is targeted to a specific tumor cell type against which the antibody is directed. The linking of cytotoxic agents to antibodies to make xe2x80x9cimmunotoxinsxe2x80x9d has been reported. Of particular interest have been immunotoxins of monoclonal antibodies conjugated to the enzymatically active portions (A chains) of toxins of bacterial or plant origin such as Ricin or Abrin. Nevelle and York, Immunol. Rev. (1982) 62: 75-91; Ross et al., European J. Biochem. (1980) 104; Vitteta et al., Immunol. Rev. (1982) 62: 158-183; Ross et al., Cancer Res. (1982) 42: 457-464; Trowbridge and Domingo Nature (Cond.) (1981) 294: 171-173. Immunotoxins have been prepared by conjugating MoAbs with toxins or fragments of toxins derived from plants. Gelonin and ricin are among the most active plant derived toxins in inhibiting protein synthesis.
Although antibodies have been used as delivery systems for toxic moieties of plant toxins and other cytotoxic drugs, conjugation of antibodies to biological response modifiers such as tumor necrosis factor and the use of such conjugates as specific delivery system to target tissues or cells has not heretofore been possible.
The prior art remains deficient in the lack of effective means to treat a wide variety of human cancers. The prior art fulfils this longstanding need and desire in the art.
The present invention is directed to a novel antibody delivery system for biological response modifiers. The present invention provides a composition which is an immunoconjugate of an antibody directed toward a cell associated antigen covalently bound to a biological response modifier. Preferably, the antibody is directed toward a cell associated antigen specific for a tumor cell. In one embodiment, the immunoconjugate comprises an antibody, preferably a monoclonal antibody covalently coupled to a biological response modifier. Alternatively, the immunoconjugate may be a fusion protein prepared by genetic engineering methods known to those in the art. Such a fusion protein would contain the antigen recognition site of an antibody molecule and the cytotoxic moiety of a biological response modifier.
In one embodiment, the invention provides a cytotoxic composition which selectively binds to and kills tumor cells. These target tumor cells may be of any tumor which has or produces an antigenic marker in amounts greater than that found in or on normal cells. While preferably the antigenic marker is a cell surface antigen, the present invention is equally applicable to tumor cells which produce an intracellular antigen in amounts greater than normally produced by normal cells. It is known that many tumors produce intracellular antigens and either secrete them or release these antigens when the tumor becomes necrotic.
It can readily understood that the immunoconjugate of the present invention may be utilized to target delivery, not only of cytotoxic Biological Response Modifiers to selected target cells, but also to selectively deliver any biological effector to a selected target site as long as said target site contains an antigenic marker at a concentration in excess of that found at other non-target sites.
In another embodiment, the invention provides cytotoxic compositions which selectively bind to and are cytotoxic for or cytostatic for human breast cancer cells, cervical carcinoma cells, and melanoma cells. In another embodiment, this invention provides a method of killing human breast cancer cells, cervical carcinoma cells, melanoma cells or other tumor cells expressing tumor associated antigen by contacting the cells with a cytocidally effective amount of the immunotoxin composition of the present invention. In one embodiment, the immunoconjugate of the present invention is used to deliver a cytotoxic immunoconjugate to breast tumor cells which express the 15A8 antigen. In yet another embodiment the present invention provides an immunoconjugate that binds to and is cytotoxic or cytostatic for melanoma tumor cells. In yet another embodiment the present invention provides an immunoconjugate that binds to and is cytotoxic or cytostatic for cells which express the ZME-018 antigen or a functional equivalent thereof. The immunoconjugate of the present may also comprise an antibody which recognizes a cytoplasmic antigen including, but not limited to, the 465.12 antibody of Wilson which reacts with a melanoma cytoplasmic antigen.
It is an object of the invention to provide conjugates of antibodies with biological response modifiers.
It is another object of the present invention to provide a composition of matter comprising a conjugate of an antibody directed toward a tumor associated antigen and a biological response modifier moiety.
It is another object of the present invention to provide a composition comprising a recombinantly produced compound comprising an antibody moiety and a biological response modifier, which biological response modifier may be an cytoactive moiety of said biological response modifier.
Another object is to provide a method of treating proliferative cell diseases such as, for instance, cancer, comprising administration of a cytocidally effect dose of an immunoconjugate comprising an antibody or antibody moiety directed to a TAA on the target cell conjugated with a biological response modifier or cytoactive moiety thereof to an individual in need of said treatment.
It is a further object to provide an immunoconjugate that is a gene-fusion product recombinantly produced by fusion of a gene coding for the antigen recognition site of a monoclonal antibody with a gene coding for a biological response modifier or the cytoactive moiety thereof, such as cytokines or lymphokines, and preferably TNF.
It is a further object to provide a method of suppressing secondary cataract formation which comprises administration of the immunoconjugate of the present invention to an individual after the surgical replacement of the optic lens.
It is a further object of the present invention to provide a composition comprising an antibody directed to a tumor-associated antigen such as a breast tumor associated antigen or a melanoma conjugated with a biological response modifier such as TNF.
It was a further object of the present invention to provide a pharmaceutical composition comprising an immunoconjugate of a biological response modifier such as TNF in a pharmaceutically acceptable carrier.
An exemplary sample of hybridoma ZME-018 which produces an antibody recognizing the ZME-018 antigen was deposited on Apr. 7, 1992 with the American Type Culture Collection at 12301 Parklawn Drive, Rockville, Md., and received the accession designation HB 11009.